/Engine/Source/Runtime/Engine/Public/ImageUtils.h
Compress image to thumbnail enabled format (png or jpg) uint8 array.
static void ThumbnailCompressImageArray ( int32 ImageWidth, int32 ImageHeight, const [TArray](API\Runtime\Core\Containers\TArray)< [FColor](API\Runtime\Core\Math\FColor) > & SrcData, [TArray](API\Runtime\Core\Containers\TArray)< uint8 > & DstData )